Vascular complications in patients with type 2 diabetes: prevalence and associated factors in 38 countries (the DISCOVER study program)

Abstract

Background: The global prevalence of type 2 diabetes-related complications is not well described. We assessed prevalence of vascular complications at baseline in DISCOVER (NCT02322762; NCT02226822), a global, prospective, observational study program of 15,992 patients with type 2 diabetes initiating second-line therapy, conducted across 38 countries.

Methods: Patients were recruited from primary and specialist healthcare settings. Data were collected using a standardized case report form. Prevalence estimates of microvascular and macrovascular complications at baseline were assessed overall and by country and region, and were standardized for age and sex. Modified Poisson regression was used to assess factors associated with the prevalence of complications.

Results: The median duration of type 2 diabetes was 4.1 years (interquartile range [IQR]: 1.9-7.9 years), and the median glycated hemoglobin (HbA_1c) level was 8.0% (IQR: 7.2-9.1%). The crude prevalences of microvascular and macrovascular complications were 18.8% and 12.7%, respectively. Common microvascular complications were peripheral neuropathy (7.7%), chronic kidney disease (5.0%), and albuminuria (4.3%). Common macrovascular complications were coronary artery disease (8.2%), heart failure (3.3%) and stroke (2.2%). The age- and sex-standardized prevalence of microvascular complications was 17.9% (95% confidence interval [CI] 17.3-18.6%), ranging from 14.2% in the Americas to 20.4% in Europe. The age- and sex-standardized prevalence of macrovascular complications was 9.2% (95% CI 8.7-9.7%), ranging from 4.1% in South-East Asia to 18.8% in Europe. Factors positively associated with vascular complications included age (per 10-year increment), male sex, diabetes duration (per 1-year increment), and history of hypoglycemia, with rate ratios (95% CIs) for microvascular complications of 1.14 (1.09-1.19), 1.30 (1.20-1.42), 1.03 (1.02-1.04) and 1.45 (1.25-1.69), respectively, and for macrovascular complications of 1.41 (1.34-1.48), 1.29 (1.16-1.45), 1.02 (1.01-1.02) and 1.24 (1.04-1.48), respectively. HbA_1c levels (per 1.0% increment) were positively associated with microvascular (1.05 [1.02-1.08]) but not macrovascular (1.00 [0.97-1.04]) complications.

Conclusions: The global burden of microvascular and macrovascular complications is substantial in these patients with type 2 diabetes who are relatively early in the disease process. These findings highlight an opportunity for aggressive early risk factor modification, particularly in regions with a high prevalence of complications. Trial registration ClinicalTrials.gov; NCT02322762. Registered 23 December 2014. https://clinicaltrials.gov/ct2/show/NCT02322762 . ClinicalTrials.gov; NCT02226822. Registered 27 August 2014. https://clinicaltrials.gov/ct2/show/NCT02226822.

Keywords: Observational study; Type 2 diabetes; Vascular complications.

Fig. 1

Age- and sex-standardized prevalence of a microvascular and b macrovascular complications, according to region and country. Percentages calculated for all patients with data available; unreported data are excluded. UAE United Arab Emirates

Fig. 2

Multivariable analysis of factors associated with a microvascular and b macrovascular complications. ^aRRs adjusted for all variables in the figure with the addition of SBP, total cholesterol levels and comedication use, using a modified Poisson model with cluster-based sandwich variance estimator as described in “Methods”. RRs for the associations between complication prevalence and SBP, total cholesterol levels, and comedication use are not reported due to reverse-causality. ^bMinor hypoglycemic event in the previous month or major hypoglycemic event in the previous year. BMI body mass index, CI confidence interval, HbA_1c glycated hemoglobin, RR rate ratio